One of the smoothest and effortless drivers of my main system. Does exactly what an amp should do, let the source shine through good speakers without coloring the sound. Button switches are a minor pain, needing to be cleaned once in a while, but worth it for the pure power it provides. I'll never let mine go.

I was never fun of Harman Kardon as brend, but few years ago I tested PM665 with tube pream and result was just...great..!! I dont know about other models of HK but this one really surprice me, I got more than I expected. Mixing transistor with tubes is what I do so many years, this result was amazing. HK output sound is neutral and well balanced so intervention should be with colourful tube preamp...Mullard, Philips tubes. Avoid Telefunken or Siemens tubes otherwise you will get nothing....funeral..:)
Highly recommend in hybrid combination with tube preamp...